66 THE ARMY WORM 



habits of life are very similar to those of the common cutworms 

 to which, indeed, the armv worms are closely related. It is 

 only when these insects become so excessively numerous that 

 they exhaust the food supply of the field in which they develop, 

 that the "army" habit is assumed. Then, however, they are 

 forced to seek new quarters for food, and as their only mode of 

 progress is by crawling along the ground, they move in solid 



Fig. 4. Moths of Army Worm : natural size. (Original). 



masses toward adjacent fields. " Their numbers at these 

 times," wrote Dr. C. V. Riley, "are often so enormous, and 

 their voracity so great, that it is impossible for one who has 

 not been an eye witness to appreciate it fully. * * * The 

 army worm when traveling will scarcely turn aside for anything 

 but water, and even shallow water courses will not always 

 check its progress, for the advance columns will often con- 

 tinue to rush headlong into the water until they have suffi- 

 ciently choked it up with their dead and dying bodies to ena- 

 ble the rear guard to cross safely over. I have noticed that 

 after crossing a bare field or bare road where they are sub- 

 jected to the sun's rays, they would congregate in immense 

 numbers under the first shade they reached. In one instance I 

 recollect their collecting and covering the ground five or six 

 deep all along the shady side of a fence for about a mile, 



